The present invention relates to a radio receiving system, and in particular to a vehicle radio reception system that automatically remains tuned to the strongest frequency of a desired transmitter.
Radio receivers with a so-called autobest functionality have been known for some time. These receivers, which are mainly used for car radios, automatically seeks another frequency of the same transmitter and tunes to this frequency, when the reception quality of a transmitter to which they are tuned falls below a certain limit. Even when a driver travels over large distances, which exceed the range of an individual USW broadcast station, he is thus able to continue listening to a transmitter without having to manually seek an alternate frequency when reception on the presently set frequency becomes unsatisfactory.
However, these receivers do not provide uninterrupted listening, since the process of seeking a frequency of the same transmitter can take considerable time, within which the receiver repeatedly tunes to other frequencies and checks whether the transmitter received there is identical to the original one. If such an interruption automatically occurs during a transmission of traffic reports, such as warnings of a traffic jam, etc., this is extremely annoying for the user, even if the interruption takes only a few seconds.
Such interruptions of reception can be avoided by a radio receiving system of the type described in the published German patent application DE 196 18 755 A1. The receiving system disclosed in this published application includes a plurality of autobest receivers, all of which are tuned to the same transmitter and, over a ring, mutually exchange data which contain the reception signal and information about the reception quality of the individual receivers. A receiver that obtains such data from an adjoining receiver on the ring replaces these data by its own reception signal and the associated quality information, if the quality of its own signal is better than that of its adjoining receiver. If its own reception quality is worse, the signal obtained from the adjoining receiver is passed along unchanged. Consequently, the reception signal circulating on the ring is output as an audio signal, and is the best among the reception signals of all the receivers. If the quality of a receiver becomes so bad that it must seek a new reception frequency, this change is inaudible to a user of the radio reception system as long as there are other receivers on the ring that can output a reception signal with satisfactory quality. A problem with this system is that since every receiver seeks an alternative frequency only until it has found one with satisfactory quality, the reception signal circulating on the ring generally does not constantly have the best quality, which is achievable by taking into account all the available frequencies of a transmitter.
Therefore, there is a need for a radio reception system that includes a plurality of radio receivers, configured and arranged to ensure that the receiver configured as an audio receiver is automatically tuned to receive the best possible reception frequency for a desired transmitter.